Managing method

ABSTRACT

A method for managing a pumping device ( 10 ) suitable, in use, to supply in a periodic pulsed manner a plurality of given quantities (Q) of a given fluid (M) so as to generate a flow of said given fluid (M) presenting a first given average flow rate (PM 1 ); the supply of each given quantity (Q) being both preceded and followed by respective first pauses (P 1 ) in the supply of the given fluid (M) presenting a first given duration (T 1 ); the method in question comprising at least a phase of stopping the pumping device ( 10 ) so as to introduce at least a given second pause during the supply of at least a quantity (Q) of the given fluid (M).

The present invention relates to a managing method. In particular, thepresent invention relates to a method for managing a pumping device. Inmore detail, the present invention relates to a managing method, whichcan be used to adjust the flow of a fluid supplied through a pumpingdevice.

BACKGROUND TO THE INVENTION

The use of peristaltic pumps is well known in many sectors whenever itis necessary to pump a fluid maintaining it insulated inside arespective pumping circuit, so as to avoid the fluid entering intocontact with the outside environment, thus preventing contaminations.Peristaltic pumps are widely used for example in the food industry andin the hospital sector where it is necessary, for hygienic reasons, topump fluids under conditions of high cleanliness or even undercontrolled atmosphere and/or in sterile environment.

As it is well known, a peristaltic pump is provided with a highlyelastic flexible tube, made typically of natural rubber, Hypalon orpolypropylene, which is peripherally compressed by at least onemechanical pressing member, for example a roller, which occludes thelumen of the tube. Each of these pressing members, in use, is made slidelongitudinally along the tube so that the “squeeze” generated by itdisplaces in a concordant and continuous manner along the tube andpushes the fluid, contained inside the pumping circuit, in the samesliding direction as the rollers. In more detail, there are varioustypes of peristaltic pumps: for example, in the medical sector linearperistaltic pumps are commonly used, wherein a flexible tube is arrangedlinearly and is engaged in sequence and in a periodic manner by aplurality of rotating and coaxial cam members, identical to each otherand reciprocally synchronised. Alternatively, the rotary peristalticpumps are well known, which are characterised by compactness and greatsturdiness. This type of pumps provides for the use of a stator unit,which presents a first central cylindrical seat housing a respectiverotor provided peripherally with a plurality of rollers. The stator unitfurthermore presents a second seat, that is substantially semi-toroidal,to house stably an elastic tube, which is therefore folded along atleast an arc of a circle concentric with the axis of rotation of therotor holding the rollers. These rollers, in use, peripherally push thetube, thus generating squeezes thereof which, in use, slidelongitudinally and cyclically along the tube in a concordant manner asthe rotation of the rotor.

Independently of the respective type, each peristaltic pump is suitableto supply each respective fluid pumped by it in a periodic pulsed, andthus inevitably discontinuous, manner. Actually, the presence of eachsqueeze, which causes the pumped fluid to move forwards, causesinevitably a stop, or at least a sudden reduction, and therefore adiscontinuity, in the supplied fluid and this discontinuity will occurperiodically whenever the squeeze passes at the inlet of the deliveryduct of the pump.

The presence of these discontinuities in the supply flow of aperistaltic pump represents a great disadvantage for the use of thesedevices when it is necessary to pump a fluid with a very low flow rate,for example in the order of 1 ml/min, corresponding to a regime ofrotation lower than 5 rpm. It should be noted, in fact, that in order tosupply reduced flow rates of fluid, the sliding speed of the pressingmembers along the tube is usually minimised, and this entails that theduration of each stop/discontinuity in the supply is prolonged, with theresult that the supplied flow is not substantially uniform but, on thecontrary, it presents significant non-uniformities. In this regard itshould be noted that the American firm Abbott Laboratories is the holderof the patent U.S. Pat. No. 5,219,279 relating to a volumetric pump andto an operative method thereof, which allows to supply a flow rate offluid which can be defined substantially at will by the user. Inparticular, this volumetric pump comprises a gear motor, which actuatesa pumping device provided to engage the flexible tube, transporting thefluid to be pumped, with a respective cam member.

This pumping device is designed so that 24 rotations of the gear motorcorrespond to each pumping cycle, in order to allow a fine adjustment ofthe position of the cam member engaging the tube. At this point itshould be noted that the document U.S. Pat. No. 5,219,279 specifies thatit is possible to adjust, substantially at will, the average flow rateof the supplied fluid by varying the speed of the gear motor andinserting a given number of pauses of given duration during the pumpingcycles of the cam member; however, as clearly shown in FIG. 22 of thementioned document, the supplied fluid, although presenting the desiredaverage flow rate, is not uniform, but on the contrary it alternates afirst phase, wherein the supply of fluid is greatly pulsed, with asecond phase, wherein the supply is substantially continuous. It shouldbe furthermore noted that, in order to obtain such a fine adjustment ofthe average flow rate of supplied fluid, the volumetric pump in questioncomprises a more complex and more expensive pumping device, whichrequires more maintenance than the common rotary peristaltic pumps.

Alternatively, the American firm Baxter International Inc is holder ofthe international patent application WO96/01371, describing and claiminga peristaltic pumping system for medical applications, suitable tosupply a fluid with a flow rate which can vary between a maximum of 170ml/min and a minimum value lower than 10 ml/min. At this end, thepumping system comprises a rotary peristaltic pump provided with a motorwith variable rotational speed, and with a control device, suitable tocontrol an alternate actuation of the respective rotor so as tointroduce slowdowns or pauses in the supply, aimed at reducing theaverage flow rate of the pumped fluid. This pumping system thereforeallows to supply fluid with a reduced average flow rate which can bedefined at will, but, on the other hand, it is not suitable to overcomethe drawbacks due to the discontinuity of the flow of supplied fluid. Inparticular, the teachings of the document WO96/01371 are based upon theapproximation that the fluid supplied by the respective pumping systemis continuous when the rotor works with a constant angular speed.Consequently, this document takes only the average flow rate of theperistaltic pump into consideration, and not the presence of the pausesof the supplying phase, which are intrinsic to the peristaltic structureof the pumping system. Therefore, the insertion of pauses during eachsupplying phase, even though it allows reducing the average flow rate ofthe supplied fluid, amplifies the non-uniformity of the flow of fluidsupplied by the rotary peristaltic pump. It should be furthermore notedthat the method for managing the pumping system described in thedocument WO96/01371 provides:

-   -   a fixed number of pauses/slowdowns for each pumping cycle;    -   that by varying the desired average flow rate of supply, the        duration of the phase of effective supply varies substantially        in inverse proportion to the duration of the pauses/slowdowns in        supply. It is therefore readily apparent that, when extremely        reduced average flow rates are chosen, the flow supplied by the        pumping system according to the document WO96/01371 will present        high discontinuities, as short periods of effective supply are        followed by long periods of pause/reduction in the supply.

Moreover, a known alternative solution to increase the uniformity of aflow supplied by a rotary peristaltic pump is that of increasing thenumber of rollers carried by the respective rotor; this solution howeverentails higher production and maintenance costs, and is thereforeexcessively expensive for the largest part of the sectors wherein therotary peristaltic pumps are commonly used.

Therefore, in view of the above description, the problem of managing aperistaltic pumping device so that it is suitable to supply continuouslyand substantially uniformly flows of reduced flow rate, definable atwill, is currently unsolved and represents an interesting challenge forthe applicant, that aims at obtaining a managing method which can beimplemented on a simple and economical peristaltic pumping device andwhich is suitable to solve the above illustrated problems.

SUMMARY OF THE PRESENT INVENTION

The present invention relates to a managing method. In particular, thepresent invention relates to a method for managing a pumping device. Inmore detail, the present invention relates to a managing method whichcan be used to adjust the flow of a fluid supplied through a pumpingdevice.

The object of the present invention is to provide a method which can bevalidly used to manage a pumping device preferably of the peristaltictype; this method allows to solve the above illustrated drawbacks, andit is therefore suitable to satisfy a plurality of requirements that todate have still not been addressed and therefore suitable to represent anew and original source of economic interest, capable of modifying thecurrent market of the pumping devices.

According to the present invention, a managing method is provided, whosemain characteristics will be described in at least one of the appendedclaims.

BRIEF DESCRIPTION OF DRAWINGS

Further characteristics and advantages of the managing method accordingto the present invention will be more apparent from the descriptionbelow, set forth with reference to the accompanying drawings anddiagrams, which illustrate at least one non-limiting example ofembodiment, in which identical or corresponding phases of the method areidentified by the same reference numbers. In particular:

FIG. 1 is a schematic perspective view of a pumping device suitable toimplement a managing method according to the present invention;

FIG. 2 illustrates diagrams relating to the supply of fluid through thepumping device of FIG. 1, functioning according to a first operatingmode;

FIG. 3 illustrates diagrams relating to the supply of fluid through thepumping device of FIG. 1, functioning according to a second operatingmode;

FIG. 4 illustrates diagrams relating to the supply of fluid through thepumping device of FIG. 1, functioning according to a third operatingmode; and

FIG. 5 illustrates diagrams relating to the supply of fluid through thepumping device of FIG. 1, functioning according to a variant of thethird operating mode of FIG. 4.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

In FIG. 1, number 1 indicates, in its entirety, a pumping device 10comprising a pump 15 provided with an inlet duct 11, which can be usedto supply a fluid M to the pump 15, and an outlet duct 12, through whicheach pumped portion of fluid M is supplied. It should been noted thathereinafter the term fluid M will indicate not only a liquid or a gas,but any type of flowable substance, i.e. any type of substance whichpresents macroscopically viscosity features substantially equivalent tothose of a fluid and which can be therefore easily transported through aduct or a tube.

In particular, as illustrated in FIG. 1, the pump 15 preferablycomprises a peristaltic pump suitable to supply the fluid M from theoutlet duct 12 in a pulsed manner, i.e. through an intermittent andperiodic supply of given quantities (jets) of fluid M alternated withrespective pauses in the supply. In fact, as it is well known, thepreviously illustrated functioning principle upon which the peristalticpumps are based intrinsically entails the presence of at least firstpauses P1 in the supply of the fluid M, caused by the passage of asqueeze of the tube associated with a respective pressing member, at theentrance of the outlet duct 12.

In particular, with reference to FIG. 1, it should be noted thathereinafter reference will be made to a peristaltic pump 15 of therotary type provided with a stator unit 16 housing an elastic tube 17and with a rotor 18 provided with at least a pressing roller 19. Therotor is carried into rotation by an actuator, known and therefore notillustrated, for example a DC electric motor or a brushless motor, so asto be suitable to rotate with a given and constant angular speed V,which hereinafter will be considered fixed for the sake of simplicity.

In use, when the rotor 18 rotates continuously at this angular speed V,the pumping device 10 will be suitable to supply the fluid M with a flowrate, whose time dependence, and therefore the dependence from theangular position a of the rotor 18, is illustrated in FIG. 2 a. Fromthis FIG. 2 a it is clearly understood that, when the pumping device 10operates according to this first operating mode A, wherein the rotor 18rotates continuously at a constant angular speed V, the flow rate of thesupplied fluid M is pulsed and periodic. In more detail, to eachcomplete rotation, or cycle, of the rotor 18, a number of supply periodsT corresponds, equal to the number of the rollers 19 carried by therotor 18. In this regard it should be specified that hereinafter theterm supply period T will indicate the time period comprised between theend of two first pauses P1. Therefore, with reference to the preferredembodiment of FIG. 1, the pump 15 will be preferably provided with tworollers 19 peripherally carried in diametrically opposite positions, andit will therefore present a rotation cycle equal to two supply periodsT.

With reference to FIG. 2 again, each period T will correspond to the sumof the duration TQ of a phase of supply at a constant flow rate PC of aquantity Q of the fluid M, and the duration T1 of a first pause P1. Itis furthermore clearly apparent that, even if pulsed, the flow of thefluid M, supplied by the pumping device 10 functioning in the firstoperating mode A, presents a first average flow rate PM1 equal to theration between the quantity Q and the duration of the period T andclearly lower than the constant flow rate PC.

Now, with reference to FIG. 2 b, it is possible to note that the fluid Msupplied by the pumping device 10 growths over time (and relative to theangular position a of the rotor 18) according to a substantially steppedgraph presenting a height which is a whole multiple of the quantity Qwherein each “plateau” represents a first pause P1.

With reference to FIG. 1, the pumping device 10 comprises a control unit20 electrically connected to the actuator associated with the rotor 18so as to be suitable, in use, to control actuations of this rotor 18 andto monitor, second by second, the angular position a of the rotor 10. Inparticular, this control unit 20 comprises a CPU 25 of the programmabletype and it is provided with a memory 21 and with an interface 22,through which a user can select operating modes for the pumping device10 and/or insert the value to be assigned to parameters of supply.Alternatively, if the pumping device 10 is part of a more wideapparatus, this interface can be connected to a computer, suitable toperform a program for supervising the supply of the fluid M and,therefore, enabled to control the operation of the pumping device 10.

In particular, the memory 21 stores the numerical values of a function,which associates the flow of the fluid M, which can be supplied in useby the pumping device 10, with an independent variable such as, forexample, the pumping/rotation time of the rotor 18 or the angularposition a of the rotor 18. Just by way of example again, the memory 21can preferably, but without limitation, contain the numerical data ofthe function illustrated in FIG. 2 a and the control unit 20 will betherefore enabled to calculate easily the values of the functionillustrated in FIG. 2 b by means of simple operations of numericalintegration. In other words, as the memory 21 contains information aboutthe flow rate of the pumping device 10, the control unit 20 is suitableto calculate the precise quantity of supplied fluid M as a function ofthe pumping/rotation time of the rotor 18 and/or of the angular shiftdescribed by the rotor 18.

Therefore, thanks to this feature of the control unit 20, the pumpingdevice 10 is suitable to work according to an operating mode B, whereindoses Q′, definable substantially at will, of fluid M are supplied in anintermittent manner. In more detail and with particular reference toFIG. 3, when the pumping device 10 operates in this second operatingmode B, the control unit 20 puts the rotor 18 into rotation exactly forthe time necessary to supply a dose Q′ and, at this point, stops therotation of the rotor 18 and waits for a time interval of duration T2,which can be defined substantially at will by the user through theinterface 22. Therefore, when functioning in the second operating modeB, the pumping device 10 is suitable to supply doses Q′ alternated withsecond pauses P2 in supply having duration T2.

With particular reference to FIGS. 2 and 3 again, it should be notedthat the data contained in the memory 21 allow to take into account alsothe presence of the first supply pauses P1 and therefore, contrarily towhat occurs in the prior art, the pumping device 10 is suitable tosupply in a repeatable manner a plurality of doses Q′ of fluid Msubstantially identical to each other. Clearly, in the particular casein which the end of the supply of a dose Q′ corresponds to the end ofthe supply of a quantity Q, and therefore to the beginning of a firstpause P, the rotor 18 will continue its run for a time interval ofduration T1 and it will then stop for a time interval presenting aduration substantially identical to the difference between the durationT2 and the duration T1 so that, in this case, the first pause P1 isoverlapped with the respective second pause P2.

In any case, the control unit 20 calculates the exact angular positionof stopping of the rotor 18 to obtain each required dose Q′ and it istherefore suitable to synchronise the chronological arrangement of eachsecond pause P2 relative to at least one first pause P1 so as to supplydoses Q′ precisely. This feature of the pumping device 10 isparticularly useful when one desires to supply first doses Q′ reducedrelative to the quantity Q as, in the pumps designed according to theprior art, these reduced doses are subjected to high uncertainties insupply and non-uniformities due to the presence of the first supplypause P1.

At this point, with reference to FIG. 4, it should be noted that thepumping device 10 is suitable to operate also according to a thirdoperative mode C, wherein the fluid M is supplied in a substantiallyuniform manner with a second average flow rate PM2 which is lower thanthe first average flow rate PM1 and which can be defined substantiallyat will by the user. In particular, to enable this third operative modeC, the control unit 20 controls an alternate actuation of the rotor 18,wherein this rotor 18 is repeatedly actuated for a time interval ofduration TQ″ and subsequently stopped for a time interval of durationT3. In other words, as it is clear apparent from FIG. 4 a, the thirdoperative mode C of the pumping device is based upon the introduction ofa given number of third pauses P3 in the rotation of the rotor 18 duringthe supply of each quantity Q, which is therefore subdivided in adiscrete number of fractions Q″.

At this point, it should be noted that the third operative mode C issignificantly different from what seen in the prior art, wherein therotor of the peristaltic pump is brought to a respective minimum angularspeed and, for each period, once the quantity Q has been completelysupplied, this rotor is stopped for a given time interval, so that thesupplied average flow rate corresponds to the value set by the user.However, in this operative mode, which is typical of the prior art, longsupply phases alternate with long pauses, and therefore the flow ofsupplied fluid is significantly non-uniform.

Vice versa, in the managing method according to the present invention,when the pumping device 10 operates according to the third operativemode C, the rotor 18 is alternatively stopped and brought to the angularspeed V for a plurality of times during the supply of each quantity Q offluid M, thus obtaining a supplied flow which is substantially uniformover time.

In particular, it should be noted that, based upon the flow rate set bythe user, the control device 20 will determine the number and theduration T3 of the third pauses P3, which shall be inserted during thesupply of each quantity Q of fluid. As it is clearly apparent from FIG.4 again, the control device 20 is designed so as to select a givennumber of third pauses P3 according to the required flow rate and insuch a manner that all these third pauses P3 present a same duration T3substantially of the same order of magnitude of the duration T1 of thefirst pauses P1. In fact, as the angular speed V is constant, theduration T1 of the first pauses P1 is fixed and it is connected with theintrinsic structural features of the pump 15, whilst the duration ofeach third pause P3 is controlled by the control unit 20 and isconnected both with the flow rate chosen by the user and by the numberof third pauses P3 inserted in each supply period T comprised betweenthe end of two consecutive first pauses P1. At this point, withreference to FIG. 4 again, it should be noted that the third pauses P3are distributed during each supply period T in a substantially uniformmanner between the end of a first pause P1 and the beginning of thesubsequent first pause P1; more in particular, each group of thirdpauses P3 inserted during the supply of a quantity Q of fluid M resultssynchronised relative to the pair of consecutive first pauses Pl, whichchronologically delimit the supply of this quantity Q, in such a mannerthat the flow of supplied fluid M, even though it result“microscopically” pulsed, presents a flow rate which is substantiallyuniform over time, independently of the value chosen by the user forthis flow rate.

In this regard, it should be specified that, in order to maximise theuniformity over time of the flow of supplied fluid M, the control unit20 is programmed so as to select a given number N of third pauses P3 tobe introduced during the supply of each quantity Q based upon the valueof the average flow rate PM2 assigned by the user. In particular, thecontrol unit 20 is preferably enabled to select the given number N amonga plurality of whole values, preset during the programming phase, sothat to each value of the second average flow rate PM2 assigned by theuser, a unique whole value can be associated, preset for the givennumber N. At this end, it is possible to subdivide all the values whichcan be assigned to the second flow rate PM2, i.e. all the values of flowrate comprised between zero and the first average flow rate PM1, in adiscrete plurality of intervals, or fields, of flow rate, mathematicallycontiguous to each other, and to associate to each of these fields apreset whole value which can be assigned to the given number N. In use,once a value has been assigned to the second average flow rate PM2, thecontrol unit 20 will identify the field containing this second averageflow rate PM2 and will assign the respective preset whole value to thegiven number N.

At this point, once the given number N of third pauses P3, associatedwith the supply of each quantity Q, has been defined, the control unit20 will calculate the duration of the supply time intervals TQ″ and thedurations T3 of the third pauses P3. With reference to FIG. 4, it isclear that N+1 phases of supplying a fraction Q″ will correspond to Nthird pauses P3 for each supply of a quantity Q, and therefore thedurations T3 and TQ″ can be calculated, for instance, according to thefollowing formulas:

$\quad{\begin{matrix}{{TQ}^{''} = \frac{TQ}{N + 1}} \\{{T\; 3} = \frac{{{PM}\; {2/Q}} - {TQ} - T}{N}}\end{matrix}}$

Anyway, independently of the algorithms used to calculate the durationsT3 and TQ″, it should be noted that, during the phase of programming thecontrol unit 20, each preset whole value has been associated to arespective flow rate field, so that the durations T1, TQ″ and T3 presentsubstantially identical values or anyway values of the same order ofmagnitude, in order to maximise the uniformity over time of the flow ofsupplied fluid M.

Alternatively, instead of associating a preset whole value for each flowrate field, it is possible to give to the control unit 20 the task ofcalculating, every time, a given number N based upon the value of thesecond average flow rate PM2 inserted by the user. In this case, thechoice of N could be made, for example, through an algorithm ofmaximisation of the uniformity over time of the flow rate of the flow ofsupplied fluid M; this algorithm can be implemented, for example butwithout limitation, by means of a numerical procedure of minimisation ofthe sum of the square numbers of the differences between T3 and TQ″relative to T1.

At this point, it would be advisable to note that the pumping device 10,when it operates according to the third operative mode C, is suitable tosupply a flow of fluid M, which simulates the flow which can be suppliedby a rotary peristaltic device provided with N+1 rollers. As it is wellknown, the greater the number of rollers carried by the rotor is, thegreater the uniformity of the supplied flow is, but with higher costsfor producing and managing the peristaltic pumping device.

Therefore, thanks to the managing method illustrated above, a simplepumping device 10 provided with an economical rotary peristaltic pump 15provided with a limited number of rollers and suitable to operate onlywith a fixed and non-adjustable angular speed of the rotor, can be usedto supply continuously flows of fluid M with high uniformity and flowrate which can be set by the user substantially at will, thus simulatingthe behaviour of pumping devices provided with a greater number ofrollers and with more expensive actuators with adjustable speed.

Lastly, it should be noted a further difference between the thirdoperative mode C of the method according to the present invention andthe prior art. In the prior art, to obtain a supply of the fluid M withparticularly reduced flow rates, attempts have been made to minimise thespeed of actuation of the pump 15/of the rotor 18, thus obtaining asupplied flow non-uniform over time. Vice versa, the managing methodaccording to the present invention allows to maximise the uniformityover time of the flow of supplied fluid M by increasing the angularspeed V of the rotor 18 and it is therefore possible to state that themethod has been designed based upon a project trend opposite to thatupon which the prior art is based. In fact, as it can be noted fromFIGS. 2 and 4, by increasing the angular speed V it is possible tominimise each duration T1 and consequently also the durations T3 andTQ″, which are calculated by the control unit 20 so as to besubstantially identical to T1. Therefore, in order to obtain a samegiven flow rate PM2 when the angular speed V increases, it will besufficient to increase the given number N of third pauses P3 and,consequently, a flow will be supplied, in which the third pauses P3 andthe phases of supplying the fractions Q″ alternate with a greaterfrequency. Lastly, it is apparent by observing FIG. 4 that a flowsupplied by the pumping device 10 will be the more uniform the greaterthe given number N of third pauses P3, and therefore the greater thefrequency with which these third pauses P3 alternate with the phases ofsupplying a fraction Q″ of fluid M.

It should be however noted that in practice, in order to carry the rotor18 into rotation, it could be economically advantageous to use actuatorsprovided with limited mechanical characteristics, and thereforeunsuitable to perform a series of stops and subsequent (re)-actuationsat high frequency.

In this case, alternatively to what described above, it could beimpossible to insert a high number N of third pauses P3 during thesupply of each quantity Q and therefore, in order to supply a flowpresenting a reduced second flow rate PM2, it is possible to define areduced number N of third pauses P3 presenting a respective durationgreater than the duration T1. In more detail, with particular referenceto FIG. 5, it should be noted that it is possible to supply a flowpresenting a reduced second flow rate PM2 by reducing the given number Nof third pauses P comprised between each two first consecutive pauses P1and simultaneously by elongating the durations T3 and TQ″ so that theypresent substantially an equal value greater than the duration T1 ofeach first pause P1. In particular, with reference to FIG. 5 again, itshould be noted that, in order to guarantee the uniformity of thesupplied flow, it is necessary that each first pause P1 is followed by afourth pause P4 of stopping the rotation of the rotor 18 presenting afourth duration T4 substantially equal to the difference between thethird duration T3 and the first duration T1, so that the sum of thefirst and fourth durations T1 and T4 of each first and fourth pause P1and P4 is substantially equivalent to the duration T3 of each thirdpause P3.

In any case, in view of the above description and independently of thevariant of the third operative mode C implemented by means of thepumping device 10, the method according to the present invention is amethod for managing a peristaltic pumping device 10 which can beimplemented by means of a programmable control unit 20, provided with auser interface 22 and suitable to control the actuation of this pumpingdevice.

This method can be schematised as follows: first of all, the methodaccording to the present invention comprises a phase of selecting,through of the interface 22, an operative mode for the pumping device10. In particular, a user can select the first operative mode A whenhe/she desires to pump the fluid M in a continuous manner and at themaximum flow rate which can be obtained with the pumping device 10, orthe second operative mode B, when he/she desires to supply given dosesQ′ at regular intervals, or, lastly, he/she can select the thirdoperative mode C, when he/she desires to obtain the supply of the fluidM with a reduced flow rate which can be defined substantially at will,and in a manner substantially uniform over time.

In the first case, the phase of selecting an operative mode is followedby a phase of actuating the pumping device for an indeterminate periodof time, which will prosecute until the user or a supervision programfor supervising the control unit 20 will send a stop command. Clearly,this phase of actuating the pumping device 10 will comprise a phase ofactuating the rotor 18 into rotation with a constant angular speed V fora substantially undetermined period of time.

Moreover, in the case in which the second operative mode B is selected,the phase of selecting the operative mode will be followed by a phase ofassigning a value for the doses Q′ and, as the case may be, a phase ofassigning a value for the duration T2 of each second pause P2 interposedbetween the supply of two consecutive doses Q′. At this point, thecontrol unit 20, before supplying each dose Q′, will perform a phase ofcalculating the given angle, by which the rotor 18 must rotate so thatthe pumping device 10 will supply a quantity of fluid equal to therespective dose Q′. It is clear that this phase of calculating the givenangle of rotation of the rotor 18 is performed by the rotor 18 basedupon the data contained in the memory 21 and it can comprise, forinstance, a phase of integrating numerically a function that expressesthe flow rate of the pump 15 as a function of the angular position a ofrotation of the rotor 18, and a phase of inverting the integratedfunction obtained. It should be noted that, as the angular speed V ofthe rotor 18 is constant, each width of the angle of rotation of therotor 18 is equivalent to a given period of rotation and therefore thephase of calculating the given angle, by which the rotor 18 shallrotate, is equivalent to a phase of calculating a duration TQ′ for eachtime interval for which the rotor 18 must rotate so that the pumpingdevice 10 supplies a respective quantity of fluid equal to a dose Q′. Inthis regard and with reference to FIG. 3, it should be noted that, dueto the presence of the first pauses P1, the duration TQ′ of each phaseof supplying a dose Q′ is generally variable and therefore it should beeach time calculated by the control unit 20 based upon the datacontained in the memory 21.

At this point, following each phase of calculating a duration TQ′, themethod according to the present invention comprises a phase of actuatingthe pumping device 10/the pump 15 for a time interval of this durationTQ′, followed by a phase of stopping the supply of the fluid M for atime interval of duration T2. This phase of stopping the supply of thefluid M will comprise, according to the cases, a phase of stopping thepumping device 10/the pump 15 for a time interval of duration T2 or aphase of actuating the pumping device 10/the pump 15 for a time intervalof duration T1 followed by a phase of stopping the pumping device 10/thepump 15 for a time interval of duration T4 substantially identical tothe difference between the duration T2 and the duration T1.

In particular, the three subsequent phases of calculating a durationTQ′, of actuating the pumping device 10/the pump 15 for a time intervalof duration TQ′ and of stopping the pumping device 10/the pump 15 for atime interval of duration T2 can be repeated cyclically and in thisorder for a substantially undetermined time, so as to enable acontinuous supply of doses Q′ substantially identical to each other,until a user or a program for managing the control unit 20 sends a stopcommand.

Lastly, if the user selects the third operative mode C, the phase ofselecting an operative mode will be followed by a phase of assigning avalue for the desired second average flow rate PM2 of supply. This phaseof assigning a second average flow rate PM2 will be therefore followedby a phase of selecting the given number N of third pauses P3, whichwill chronologically subdivide the supply of each quantity Q into N+1supplies of a fraction Q″. It should be noted that this phase ofselecting a given number N of third pauses P3 can comprise a phase ofassociating a preset whole value to the given number N according to thevalue of the second average flow rate PM2, in order to maximise theuniformity over time of the flow of supplied fluid M. Alternatively,this phase of selecting a given number N of third pauses P3 can comprisea phase of calculating this given number N by means, for example, of agiven numerical algorithm of maximisation of the uniformity over time ofthe flow rate of the flow of fluid M supplied by the pumping device 10.

At this point, once the control unit 20 has selected/calculated thegiven number N, the method according to the present invention providesfor a phase of calculating the durations T3 and TQ″, so that the secondaverage flow rate PM2 resulting for the supplied flow matches the valueselected by the user. This phase of calculating the durations T3 and TQ″can comprise preferably a phase of calculating numerically the result ofthe two formulas F1 and F2 illustrated above.

At this point a phase can be performed of supplying the fluid M in amanner pulsed and presenting a substantially uniform second average flowrate PM2. This phase comprises a phase of synchronising N+1 supplyintervals of duration TQ″ and N third pauses P3 during each periodcomprised between the end of a first pause P1 and the start of thesubsequent first phase P1. These N+1 intervals of duration TQ″ and theseN pauses shall be therefore distributed in a uniform manner between eachtwo consecutive first pauses P1 and at this end the phase ofsynchronising presents the following steps in sequence:

-   -   a phase of actuating the pumping device 10/the pump 15 for a        time interval of duration TQ″;    -   a cyclic repetition, for a given number N of times, of a phase        of stopping the pumping device 10/the pump 15 for a time        interval of duration T3 and of a phase of actuating the pumping        device 10/the pump 15 for a time interval of duration TQ″; and    -   a phase of actuating the pumping device 10/the pump 15 for a        time interval of duration T1.

Alternatively, if the second variant of the third operative mode C isused, characterised by a reduced given number N of third pauses P3, theinitial phase of actuating the pumping device 10/the pump 15 for a timeinterval of duration TQ″ is immediately followed by a respective phaseof stopping the pumping device 10/the pump 15 for a time interval ofduration T4.

Briefly, the result of this synchronisation phase is that illustrated inFIG. 4 or 5, and consists in supplying a fluid M in a mannersubstantially uniform over time independently of the value selected bythe user for the second average flow rate PM2. At the same time, thissynchronisation phase allows to prevent third pauses P3 from overlappingby mistake first pauses P1, thus causing non-uniformities in thesupplied flow, similarly to what occurs in the illustrated prior art.

The managing method according to the present invention for managing theperistaltic pumping device 10 is clearly apparent from the descriptionabove and does not require further explanations. However, it could beadvisable to note that the choice of using a rotary peristaltic pump 15is merely by way of example, and does not limit the generality of themanaging method according to the present invention. In fact, themanaging method according to the present invention can be validlyapplied to all the pumping devices wherein the supplied flow presents aperiodic character similar or substantially equivalent to thatillustrated in FIG. 2.

Lastly, in view of the above description, it is clearly apparent thatthe managing method according to the present invention is suitable tosolve the technical problem in question, and it is therefore suitable tomanage a peristaltic pumping device, so that this latter is suitable tosupply in a continuous and substantially uniform manner flows of reducedflow rate which can be defined at will.

1. A method for managing a pumping device (10) of the peristaltic rotarytype provided with a rotor (18) and suitable, in use, when said rotor(18) rotates with a constant angular speed (V), to supply in a periodicpulsed manner a plurality of given quantities (Q) of a given fluid (M)in such a way so as to generate a flow of said given fluid (M)presenting a first given average flow rate (PM1); the supply of eachsaid given quantity (Q) being both preceded and followed by respectivefirst pauses (P1) in the supply of said given fluid (M) presenting afirst given duration (T1); said managing method comprising at least aphase of stopping said pumping device (10) so as to introduce at least agiven second pause (P3) during the supply of at least a said quantity(Q) of said given fluid (M); each said phase of stopping said pumpingdevice (10) comprising a phase of synchronising each said given secondpause (P3) relative to at least a corresponding said first pause (P1) inthe supply of said given fluid (M); said phase of synchronising eachsaid second pause (P3) being performable in an automatic manner throughcontrol means (20) for controlling said pumping device (10);characterised in that each said phase of stopping said pumping device(10) is both preceded and followed by a phase of supplying a givenfraction (Q″) of said quantity (Q) of said given fluid (M); each saidphase of supplying a given fraction (Q″) presenting a given secondduration (TQ″).
 2. A method according to claim 1, characterised bycomprising a phase of selecting a given number (N) of said second pauses(P3) interposed between each two consecutive said first pauses (P1) andsuitable to fractionate the supply of each said quantity (Q) of fluid(M); each said second pause (P3) being associated with a respectivephase of stopping said pumping device (10) and presenting a given thirdduration (T3) in such a way so that the flow of said given fluid (M)supplied by said pumping device (10) presents at least a second averageflow rate (PM2) lower than said first average flow rate (PM1) anddefinable substantially at will.
 3. A method according to claim 2,characterised in that each supply of a said quantity (Q) of said givenfluid (M) is carried out through a number of said phases of supplying asaid given fraction (Q″) equal to said given number (N) increased by oneunit.
 4. A method according to claim 2, characterised in that said givennumber (N) can be chosen, in use, among a plurality of preset wholevalues so as to maximise the uniformity over time of the flow rate ofthe flow of fluid (M) supplied by said pumping device (10).
 5. A methodaccording to claim 2, characterised in that said phase of selecting agiven number (N) comprises a phase of calculating said selected number(N) by means of a numerical algorithm suitable to maximise theuniformity over time of the flow rate of the flow of said given fluid(M) supplied by said pumping device (10).
 6. A method according to claim5, characterised in that said numerical algorithm is implemented bymeans of a numerical procedure of minimisation of the sum of the squarenumber of the difference between said third duration (T3) and said firstduration (T1), with the square number of the difference between saidsecond duration (TQ″) and said first duration (T1).
 7. A methodaccording to claims 2, characterised in that said phase of selecting agiven number (N) is followed by a phase of calculating said thirdduration (T3) of each said second pause (P3) and said second duration(TQ″) of each said phase of supplying a said fraction (Q″) of saidquantity (Q) in such a way so that the flow of said given fluid (M)supplied by said pumping device (10) presents said second average flowrate (PM2).
 8. A method according to claim 1, characterised in that saidphase of synchronising each said second pause (P3) comprises, followingeach said first pause (P1), the performance in sequence of a phase ofactuating said pumping device (10) for a time interval presenting saidsecond duration (TQ″); a cyclical repetition for a said given number (N)of times of a phase of stopping said pumping device (10) for a timeinterval presenting said third duration (T3) and of a phase of actuatingsaid pumping device (10) for a time interval presenting said secondduration (TQ″); and a phase of actuating said pumping device (10) for atime interval presenting said first duration (T1).
 9. A method accordingto claim 1, characterised in that said phase of synchronising each saidsecond pause (P3) comprises, following each said first pause (P1), theperformance in sequence of a phase of stopping said pumping device (10)for a time interval presenting a fourth duration (T4) substantiallyequal to the difference between said third duration (T3) and said firstduration (T1); a phase of actuating said pumping device (10) for a timeinterval presenting said second duration (TQ″); a cyclical repetitionfor a said given number (N) of times of a phase of stopping said pumpingdevice (10) for a time interval presenting said third duration (T3) andof a phase of actuating said pumping device (10) for a time intervalpresenting said second duration (TQ″); and a phase of actuating saidpumping device (10) for a time interval presenting said first duration(T1).
 10. A method according to claim 1, characterised by being suitableto simulate the supply of a flow of said given fluid (M) by a pumpingdevice (10) provided with a rotary peristaltic pump (15) equipped with anumber of respective pressing rollers (19) equal to said given number(N) increased by one unit.
 11. A method according to claim 1,characterised in that each phase of actuating said pumping device (10)consists of a phase of actuating said rotor (18) into rotation at agiven constant angular speed (V).
 12. A method according to claim 1,characterised by comprising an initial phase of selecting an operativemode of said pumping device (10) among at least a first operative mode(B), in which said pumping system (10) is suitable to supply said givenfluid (M) in a plurality of doses (Q′) substantially identical to eachother and definable substantially at will, and a second operative mode(C), in which said pumping system (10) is suitable to supplycontinuously a flow (F) of said fluid (M) presenting a flow ratedefinable substantially at will and substantially uniform over time. 13.A method according to claim 12, characterised in that said phase ofselecting the operative mode of said pumping device (10) is followed bya phase of assigning a value definable substantially at will to saidsecond average flow rate (PM2) of the flow of said given fluid (M) to besupplied through said pumping device (10); said second average flow rate(PM2) being lower than said first average flow rate (PM1).